PhaseEstimation
class PhaseEstimation(num_evaluation_qubits, unitary, iqft=None, name='QPE')
Bases: qiskit.circuit.quantumcircuit.QuantumCircuit
Phase Estimation circuit.
In the Quantum Phase Estimation (QPE) algorithm [1, 2, 3], the Phase Estimation circuit is used to estimate the phase of an eigenvalue of a unitary operator , provided with the corresponding eigenstate . That is
This estimation (and thereby this circuit) is a central routine to several well-known algorithms, such as Shor’s algorithm or Quantum Amplitude Estimation.
References:
[1]: Kitaev, A. Y. (1995). Quantum measurements and the Abelian Stabilizer Problem. 1–22.
[2]: Michael A. Nielsen and Isaac L. Chuang. 2011.
Quantum Computation and Quantum Information: 10th Anniversary Edition (10th ed.). Cambridge University Press, New York, NY, USA.
[3]: Qiskit
Parameters
- num_evaluation_qubits (
int) – The number of evaluation qubits. - unitary (
QuantumCircuit) – The unitary operation which will be repeated and controlled. - iqft (
Optional[QuantumCircuit]) – A inverse Quantum Fourier Transform, per default the inverse ofQFTis used. Note that the QFT should not include the usual swaps! - name (
str) – The name of the circuit.
The inverse QFT should not include a swap of the qubit order.
Reference Circuit:
Attributes
ancillas
Returns a list of ancilla bits in the order that the registers were added.
calibrations
Return calibration dictionary.
The custom pulse definition of a given gate is of the form
{‘gate_name’: {(qubits, params): schedule}}
clbits
Returns a list of classical bits in the order that the registers were added.
data
Return the circuit data (instructions and context).
Returns
a list-like object containing the tuples for the circuit’s data.
Each tuple is in the format (instruction, qargs, cargs), where instruction is an Instruction (or subclass) object, qargs is a list of Qubit objects, and cargs is a list of Clbit objects.
Return type
QuantumCircuitData
extension_lib
Default value: 'include "qelib1.inc";'
global_phase
Return the global phase of the circuit in radians.
header
Default value: 'OPENQASM 2.0;'
instances
Default value: 16
metadata
The user provided metadata associated with the circuit
The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.
num_ancillas
Return the number of ancilla qubits.
num_clbits
Return number of classical bits.
num_parameters
Convenience function to get the number of parameter objects in the circuit.
num_qubits
Return number of qubits.
parameters
Convenience function to get the parameters defined in the parameter table.
prefix
Default value: 'circuit'
qubits
Returns a list of quantum bits in the order that the registers were added.